A liquid chromatograph mass spectrometer is one type of device for analyzing components contained in a liquid sample. In the liquid chromatograph mass spectrometer, the components in a liquid sample are temporally separated from each other through a column in the liquid chromatograph and sequentially introduced into the mass spectrometer. Each component in the liquid sample introduced into the mass spectrometer is ionized by an ion source, and the generated ions are separated from each other according to their mass-to-charge ratios.
Some mass spectrometers include another ion source into which a reference liquid sample from which an ion having known mass-to-charge ratio will be generated (“second ion source”), in addition to the ion source into which the liquid sample to be analyzed is introduced from the liquid chromatograph (“first ion source”). When such a mass spectrometer is used, mass calibration of the measurement data can be performed by detecting the ion originating from the reference liquid sample along with the ions originating from the liquid sample to be analyzed. In the case of analyzing an unknown liquid sample, it is normally necessary to prepare a plurality of kinds of different reference samples. Additionally, in the case of performing a quantitative measurement of the components in the liquid sample to be analyzed, it is necessary to prepare a plurality of kinds of reference samples which have been adjusted at known concentrations which differ from each other.
For example, a liquid sample introduction mechanism described in Patent Literature 1 is used to selectively introduce one of the plurality of reference liquid samples into the second ion source of the mass spectrometer. This mechanism includes: a passage-switching section having a plurality of sub-ports and a main port to be connected to one of the sub-ports in a switchable manner; and first liquid supply passages, each of which has one end connected to one of a plurality of liquid sample containers holding reference liquid samples and the other end connected to one of the sub-ports; and a second liquid supply passage connecting the main port and the second ion source of the mass spectrometer. With this liquid sample introduction mechanism, a reference liquid sample which is the most suitable for the liquid sample to be analyzed among the plurality of reference liquid samples can be selectively introduced into the second ion source.
A flow of an analysis performed in the liquid sample analyzing system including the previously described liquid sample introduction mechanism and a liquid chromatograph mass spectrometer is as follows:
Initially, in the liquid chromatograph mass spectrometer, an analysis controller for controlling the analyzing operation of each section of the liquid chromatograph mass spectrometer makes each section shift into a state for initiating the measurement based on the previously determined conditions for the execution of the analysis. Concurrently, in the liquid sample introduction mechanism, the passage-switching section is switched to introduce a specific kind of reference liquid sample through the second liquid-supply passage into the second ion source.
After the previously described operations have been completed in both the liquid chromatograph mass spectrometer and the liquid sample introduction mechanism, a liquid sample to be analyzed is introduced into the liquid chromatograph under the control of the analysis controller. The components temporally separated from each other by the column of the liquid chromatograph are sequentially introduced into the first ion source of the mass spectrometer. Ions are generated from both the component in the liquid sample as the analysis target introduced into the first ion source and a reference liquid sample introduced into the second ion source. Those ions are separated from each other according to their mass-to-charge ratios, and the intensity of the ions is measured at each mass-to-charge ratio.
After the completion of the measurement, the data obtained through the measurement are subjected to a predetermined post-measurement-completion process in the liquid chromatograph mass spectrometer, such as the process of adding a header for identifying the analysis to the obtained data and storing those data in a predetermined file format, or the process of detecting a peak in a chromatogram or mass spectrum.